1. Technical Field
The present invention relates generally to sensor systems and more particularly to transmission sensor systems.
2. Background of the Invention
It is well known that transmissions are assemblies that include speed-changing gears and propeller shafts through which power is transmitted from automobile engines to live axles. It is also well known that transmissions are capable of shifting to a selected speed range or vehicle operation. Smooth transition from one speed range or vehicle operation to another is facilitated through transmission range sensor systems.
Current Digital Transmission Range Sensors (DTRS) utilize a set of fixed four-bit patterns to indicate each angular position that the rooster comb/manual shaft has been placed into. For example, xe2x80x9c0000 xe2x80x9d indicates the Park position, xe2x80x9c0010 xe2x80x9d indicates the transition zone between the Park position and the Reverse position, and xe2x80x9c0011 xe2x80x9d indicates the Reverse position, etc. The transition zone bit patterns were allocated because tooling tolerances did not allow a direct change from the bit pattern of one of the manual shaft positions directly to that of the next. Resultantly, transition zones were defined as error states in software indicating a misadjusted shifter, transmission range sensor, or rooster comb system. When the operator left the shifter in a position where the detent spring rested on a peak of the rooster comb, a Powertrain Control Module (PCM) error code was set. This resulted in a false malfunction signal, which interfered with proper PCM functioning. To remedy this, the transition zones were changed from error states to manual shaft positions (PRNDL) through additional software. With this approach, though, the hydraulic positions of the manual valve did not align precisely with those of the DTRS, which necessitated narrowing of the transition zones.
An additional difficulty experienced by current DTRS systems is that they use contacting type sensors, which are subject to contact wear. As the contacts wear, fretting corrosion tends to occur which results in erroneous sensor outputs.
The disadvantages associated with these transmission range sensor systems have made it apparent that a new transmission range sensor system is needed. This new system should facilitate transition from one vehicle operation to another. The new system should also substantially reduce the likelihood of fretting corrosion errors.
It is an object of the present invention to provide an improved transmission range sensor system. It is also an object of the present invention to provide an improved transmission range sensor system for applications that include automobiles.
In accordance with the present invention, a non-contacting transmission range sensor system, which includes a control device, is disclosed. The system further includes a shaft coupled to the control device. A non-contacting range sensor, coupled to the shaft, generates a pulse-width modulated signal in response to rotation of the shaft. A control module, electrically attached to the non-contacting range sensor, is adapted to receive the pulse-width modulated signal.
Additional objects and features of the present invention will become apparent upon review of the drawings and accompanying detailed description of the preferred embodiments.